1. Field of the Invention
The present invention relates to an a.c. generator for vehicle, in particular a structure of a coil end of a stator of the a.c. generator for vehicle.
2. Discussion of Background
FIG. 18 is a perspective view of a coil end of a stator of an a.c. generator for vehicle disclosed in Japanese Unexamined Patent Publication JP-A-11-164504. In FIG. 18, a group of coils 32, 33, 34, 35, 36 inserted in an iron core 31 of the stator form stationary blades, and a path for a cooling medium is formed between coil ends. Because short sides of flat type stator winding are directed toward a surface perpendicular to an axial direction at the tops of the coil ends, although a ventilation trunk is formed for an air flowing in a radial direction to demonstrate an effect of the stationary blades, the height of the coil ends is increased, and a pressure loss of the cooling medium is increased at the tops of the coil ends, whereby a wind noise is increased, and a flow rate by a fan is decreased to thereby increase a temperature of heating element positioned on an upstream side. Further, because the ventilation trunk in the radial direction, namely a gap between coils, is formed by the stationary blades, extraneous matters are apt to intrude into the ventilation trunk, whereby cooling efficiency is spoiled; insulating coating is damaged; and therefore quality is degraded.
The conventional a.c. generator for vehicle has problems that the heights of the coil ends are increased; dimensions of the stator are increased; the length of wiring is increased; a resistance is increased; an output is decreased at time of generating electricity; and the generator is excessively heated.
Further, when the heights of the coil ends are increased, there are problems that a leak inductance at the coil ends is increased; an output is decreased; the length of the wire is increased; a cost of the wire is increased; the coil ends prevent a cooling air from flowing; and the heating element is insufficiently cooled.
Further, because the flow path for the cooling medium is formed between the coil ends, there are problems that the extraneous matters are easily intrude into an inside of the generator to cause failures; a flow of the cooling medium is made turbulent; and a wind noise is increased.
It is an object of the present invention to solve the above-mentioned problems inherent in the conventional technique and to provide an a.c. generator for vehicle, in which the heights of the coil ends are lowered and coils are arranged without interposing gaps.
According to a first aspect of the present invention, there is provided an a.c. generator for vehicle comprising:
a shaft (5) accommodated in a casing (3) and being fixed to a pulley (4) at one end;
a rotator (6) fixed to the shaft (5);
a fan (7a) located on an end surface of the rotator (6) in an axial direction;
a stator (8) assembled by a stator iron core (17) having slots and fixed to the casing (3), and a stator coil (18) accommodated in the slot; and
a rectifier (12) electrically connected to the stator coil (18) and located on a side opposite to the pulley (4),
wherein the coil ends (19) of the stator coil (18) having a cross sectional shape like a flat rectangular are constructed by first portions extending from an outer layer of a pair of slots apart from predetermined pitches in an axial direction and slanting in a circumferential direction, second portions extending from an inner layer of the other of the pair of the slots in the axial direction and slanting in the circumferential direction, and third portions positioned at ends of the coil ends (19) in the axial directions, elongated in the radial direction and connected to ends of the first and second portions in the axial direction, and in all of the first, second and third portions, long sides (300) in the cross sectional flat rectangular view of the stator coil (18) are arranged to be substantially in parallel with an end surface (17a) of the stator.
According to a second aspect of the present invention, there is provided the a.c. generator for vehicle,
wherein the third portions of the coil ends are bend in the axial direction with a curvature, and
the third portions are arranged substantially without interposing gaps therebetween.
According to a third aspect of the present invention, there is provided the a.c. generator for vehicle,
wherein connecting portions between the first portions and the third portions and between the second portions and the third portions escape each other by bending in the axial directions and the radius direction so as to avoid interference between the coil ends.
According to a fourth aspect of the present invention, there is provided the a.c. generator for vehicle,
wherein the number of slots by each pole and each phase is two or more.
According to a fifth aspect of the present invention, there is provided the a.c. generator for vehicle,
wherein a radius R of the cross sectional flat rectangular of the stator coil in the third portions of the coil ends is larger than the radius R of portions of the slots for accommodating the stator coil.
According to a sixth aspect of the present invention, there is provided the a.c. generator for vehicle,
wherein the length of the stator in its axial direction is shorter than the length of the rotator iron core in its axial direction.
According to a seventh aspect of the present invention, there is provided the a.c. generator for vehicle,
wherein lengths of the coil ends protruding from the stator iron core on both sides of the shafts are the same on both of the sides.
According to an eighth aspect of the present invention, there is provided the a.c. generator for vehicle,
wherein the length of the coil ends protruding from the stator iron core on a side of the rectifier is shorter than the length of the coil ends protruding from the stator iron core on a side of the pulley.
According to a ninth aspect of the present invention, there is provided the a.c. generator for vehicle,
wherein the fan brings an air from an inner diameter side to the outer diameter side of the coil ends for cooling the coil ends.
According to a tenth aspect of the present invention, there is provided the a.c. generator for vehicle,
wherein the fan (7a) is overlapped with the stator coil ends in the axial direction.
According to an eleventh aspect of the present invention, there is provided the a.c. generator for vehicle,
wherein the stator coil is fabricated by connecting a plurality of segment coils as electrical conductors, and
the segment coils positioned in different slots are connected after forming to bend in the circumferential direction so that open ends of the segment coils are connected.
According to a twelfth aspect of the present invention, there is provided the a.c. generator for vehicle,
wherein the rectifier (12) is located on a side at which the coil ends are turned.
According to a thirteenth aspect of the present invention, the re is provided the a.c. generator for vehicle,
wherein a varnish or a resin is located in the coil ends.